The invention relates to exhaust systems, and more particularly to improvements in the capture of an exhaust aftertreatment element such as a catalytic converter or exhaust filter.
Catalytic converter elements and exhaust filter elements are used in harsh environments. The temperature in the exhaust system cycles from ambient temperature to elevated temperatures near the exhaust gas temperature. Furthermore, vibration is induced from the engine and the vehicle or equipment that is being operated. These temperature and vibration considerations present a challenge to adequately capture an aftertreatment element, typically into a sheet metal housing in the exhaust system.
Existing aftertreatment devices typically use a ceramic fiber mat that contains vermiculite, which is known to expand with increasing temperature. The expanding mat is compressed against the element radially to provide holding force to keep the element from moving axially relative to the sheet metal body shell. The shell in turn is trapped axially within the muffler housing by an end flange. In some environments, the expanding mat may not provide sufficient holding force to keep the aftertreatment element from moving axially. In one solution known in the prior art, a stabilizer is provided by a wire mesh or rope around the aftertreatment element at the end of the expanding mat, and the sheet metal body shell is dubbed radially inwardly thereover and beyond the axial end of the element to trap and axially retain the stabilizer and the mat and the aftertreatment element. The latter dubbed-over design has improved durability as compared to the expanding mat-only design.
Commonly owned co-pending U.S. patent application Ser. No. 10/202,126, filed Jul. 24, 2002, addresses and solves a problem which was found and whose source was identified in the above noted dubbed-over design. It was found that the aftertreatment element in the dubbed-over design was still subject to movement due to the heat and/or vibration of the exhaust system. The source of this problem was identified as the dubbed sheet metal body shell itself being subject to opening up, i.e. radial outward movement, due to the heat and/or vibration of the exhaust system, which in turn allows the above noted undesirable axial movement of the stabilizer and/or mat and/or aftertreatment element. The noted opening-up problem of the dubbed-over end was solved by preventing radial outward deformation or opening-up thereof, by incorporation of a dub-retainer engaging and retaining the dubbed end of the sheet metal body shell and preventing radial outward deformation thereof otherwise caused by heat or vibration in the exhaust system.
The present invention provides another solution to the above noted problems.